Electrolytic apparatus employing filmed electrodes.



RALPH D. MERSHON AND JOHN S. RIDDILE, OF NEW YORK, N. Y.; SAID RIDDILE ASSIGNOR T0 SAID MERSHON.

ELECTROLYTIC APPARATUS EMPLOYIN'G FILMED ELECTRODES.

Application filed December 14, 1910, Serial No. 59

To all whom it may concern Be it known that we, RALPH D. MERSHON and JOHN S. RIDDILE, both citizens of the United States, and both residing at New York, in the county and State of New York, have invented certain new and useful Improvements in Electrolytic Apparatus Employing Filmed Electrodes, of which the following is a full, clear, and exact description.

The electrolytic condenser, like the electrolytic rectifier, depends for its action on the properties of the film which may be formed electrolytically upon the surface of aluminum, tantalum, magnesium and other metals when immersed in certain electrolytes and subjected to the electric current; which film possesses the singular property of allowing current to flow from the electrolyte to the electrode with little or no opposition but of strongly opposing current tending to flow from the electrode to the electrolyte. current tending to flow in the direction last indicated the film, though excessively thin, possesses high specific resistance and high dielectric strength, being able to withstand very considerable voltages without rupture, and with very inconsiderable leakage current. 7 v

The continuance of high efficiency in the performance of electrolytic apparatus of the kind referred to depends upon the preservation of the film substantially unimpaired. Moreover, unchecked impairmentof the film at any point results in more or less rapid corrosion, and ultimate destruction, of the underlying electrode. In the course of an extended study of electrolytic apparatus in which such films are formed we have observed that by suitable precautions the film may be maintained at substantially its initial high efficiency both as a dielectric medium and as a protective coating against'the attacks of the electrolyteupon the metal of the electrode, except at the boundaries of areas where the film is not in contact with the electrolyte. At the boundaries of such points or areas the film deteriorates, with accompanying loss of efficiency and corrosion of the electrode. For example, at the point where the electrode emerges from the electrolyte the film deteriorates even though it had been formed originally above such point. Similar results are observed at the boundaries of the parts covered by the electrode-supporting devices and so prevented Specification of Letters Patent.

Patented Nov. 19, 1918.

7,279. Renewed May 18, 1918. Serial No. 235,395.

from coming in contact with the electrolyte; and even the presence of a bubble of air or other gas adhering to the submerged film is usually if not always sufficient to allow the film and the electrode to be attacked at the edge of the comparatively minute area covered by the bubble.

We have accordingly been led to devise our present invention, which has for its chief object to provide an improved construction in which the boundaries or edges of the portions of the film covered by the submerged electrode-supporting devices are greatly diminished in extent, preferably to the minimum. A further object is to provide an improved construction in which the possibility of bubbles of air or other gas adhering to the submerged film is largely reduced. T 0 these and other ends the invention consists in the novel features of construction and combinations of elements hereinafter described, and more particularly set forth in the appended claims.

The invention is capable of embodiment in various different forms, and of these we have selected for illustration and specific description herein the one which at the present time we consider to exhibit the best mode of applying the invention in practice. This form is illustrated in the accompanying drawings and will now be described, with more or less detail, but the reader should keep in mind the fact that it is merely the preferred and by no means the only embodiment of the invention,

Referring to the drawings,

Figure 1 is a plan view, somewhat diagrammatic in character, of an electrolytic condenser in which our invention is embodied.

Fig. 2 is a cross section of a portion of the condenser.

Fig. 3 is a perspective view of a portion of the electrode-suppbrting frame.

Fig. 4 is a detail sectionalview of one of the spacing members employed to space the electrodes apart.

Fig. 5 is an, end oftspacing device.

The tank or receptacle containing the electrolyte is designated by 10. In this tank is the electrolyte 11, in which the electrodes 12 are submerged. In the latter the quantity ofmetal is not in general important, so long as the plates are sufficiently stiff to maintain view of a modified form must not extend from one electrode into contheir form, as the fulfillment of this condition will usually include that of a suflicient section of metal to carry the current of the plate; but it is desirable to have the plates expose as large surface as. possible to the electrolyte, and for this purpose the electrodes in our improved apparatus are made of relatively thin sheets (of aluminum, for example) suitably crimped or corrugated, as indicated in the drawing. These corrugated sheets or plates constituting the electrodes are preferably arranged with the corrugations extending vertically, so that a bubble formed on or near the surface of the electrode can rise to the surface without finding an obstacle in its path. Another advantage in the use of thin plates or sheets is that bubbles forming under the electrode are not likely to be trapped thereunder by the bottom edge of the plate, .whereas a thick plate, unless its bottom edge is rounded or beveled is apt to prevent such bubbles from floating off and rising to the surface of the electrolyte.

The electrodes are supported and spaced apart in the electrolyte preferably by the means illustrated. The means shown comprises a rectangular frame 13 of suitable material, for example aluminum, having upper and lower horizontal spacing strips or bars 14, 15, and supporting strips 16, the latter being arranged below and between the spacing members, as shown in Figs. 2 and 3.

The electrodes are placed between the spacing members, as shown in Fig. 1, and each of said members is provided with a series of spacers or spacing pins 17, the length of the pins and the intervals between the spacing members being such that the electrodes will be lightly but securely held by engagement .with the end of the pins. Any convenient method may be employed to space the plates without connecting them electrically, as for.

example by making the pins, orthe spacing members, or both, of insulating material; but it will be readily understood that if the pins are made of conducting material they tact with another. Preferably, however, the spacing membersare made of metal, and the pins of non-conducting material, for instance hard rubber, electrose, glass, steatite, etc. The pins themselves have their ends pointed or tapering and the intermediate portions are threaded to screw in threaded apertures in the spacing members, as shown in Fig. 4. Tapering or pointing the ends of the pins is an important feature, for the reason that in this way the areas of contact between the pins and the electrodes are reduced to more points, so that there is either an unbroken film of electrolyte between the tip of the pin and the electrode or the area of actual contact is so minute as to make the length of its boundary negligible. In either case there is ractically no impairment of the electrode- 1111 at the points of. engagement or the impairment is too slight to be of any real consequence. Moreover, by making the pins tapering there are no flat surfaces adjacent to the electrodes, under which bubbles may be trapped. On the contrary, a bubble formed next to the electrode and belowthe pin will float readily out from under the rounded underside of the pin and thus be permitted to rise to the surface of the electrolyte. The pins in the spacing members at the ends of the series of electrodes may be employed to space the supporting framework from the Walls of the receptacle, as indicated in Fig. 1. Instead of the pins having a single point at each end they may have a plurality of points, for example by, checkering the ends, as in Fig. 5.

The supporting members 16 are provided with similar pins, 18, the pointed upper ends of which serve to support the electrodes, while the lower ends rest on the bottom of the tank. The ins 18 thus support not only the electrodes ut also the frame in Which the spacing and supporting members are mounted. i

For the purpose of avoiding attackat the surface of the electrolyte the electrodes are wholly submerged in the liquid, and are connected with the external circuit by bus-bars 19, which are also submerged in the liquid, and which are connected to the external circuit by means of connectors .19, the submerged parts being riveted or otherwise firmly and closely attached to the plates so as to leave no cracks or pockets at the points of juncture. In order to avoid attack on the film and electrode at the edges of the busbars where they are attached to the electrode thebus-bars are made of the same metal as the electrode or of some other metal on which a similar film may be formed, so that the film will be in effect continuous from the electrode up to the surface of the electrolyte. There will be no attack on the electrodes or bus-bars, though the attached connectors may-suffer at the surface of the liquid; but the connectors are relatively small and may be renewed, whenever necessary, with little trouble and expense, much less in fact, than would be incurred in replacing the electrodes. If the stri s 19 connecting the electrodes to the bus a-rs are not integral with the former they should be connected thereto inthe same manner as the bus-bars and the connectors, that is, without cracks or pockets at the oints of juncture in which bubbles might e entrapped.

From the foregoing it will be seen that in the construction illustrated none of the surfaces which are in contact with the electrodes is of such form or character as to retain bubbles in contact with the electrode, but I on the contrary each part engaging the electrodes is so formed as to readily permit bubbles to detach themselves and float ofi to the surface of the electrolyte. The devices which position the electrodes are also of such form that their points of contact with the plates are negligibly small in extent, thus making the film practically continuous over the entire electrode. Moreover, the electrodes themselves and the bus-bars are wholly submerged in the electrolyte, so that attack at the surface-of the liquid is confined to the connectors or leads, which can be removed whenever necessary at comparatively slight trouble and expense. The electrodes are also formed to expose a large surface to the electrolyte in proportion to their volume,- and, being thin, their lower edges are too narrow to hold bubbles under them. It will of course be understood that the electrode-supporting frame is not ordinarily attacked when made of aluminum or other film-forming metal, since it is insulated from the electrodes and hence is not subjected to electrolytic action; especially when collecting electrodes are employed to bridge more or less of the electrolyte between a pair or pairs of electrodes, as described in our copending application ,filed of even date herewith, Serial No. 597,280. Electrolytic attack on the frame may also be avoided by making the side members, that is, the members which are parallel to the directioirot' the flow of current through the electrolyte, of glass or other suitable non-conducting material, so that such portions of the frame cannot act as a conductor for the current with consequent electrolytic action.

As previously stated, the invention is not limited to the form herein specifically illustrated and described, but may be embodied in other forms without departure from its proper spirit and scope as defined by the appended claims.

By the statement in the claims to the effect that theelectrode-positioning means or devices engage the electrodes at points, we mean that the areas of actual contact are substantially no larger than is necessary to afford secure support to the electrode, in contradistinction to a construction in which the areas of contact are large as for example in U. S. Patents 867,579 and 923,774.

\Vhat we claim is:

1. In an electrolytic apparatus of the kind described, the combination of a receptacle, an electrolyte therein, electrodes in the electrolyte, and a supporting frame provided with electrode spacing devices formed to engage the electrodes at points of small area and provided with members parallel to the flow of current through the electrolyte, said.

members being composed of non-conducting material.

2. In an electrolytic apparatus of the kind described, the combination of a receptacle, an electrolyte therein, electrodes in the electrolyte, and a supporting frame having spacing members arranged between the electrodes and supporting members below the electrodes, said members being provideddescribed, the combination of a receptacle containing an electrolyte, filmed electrodes of aluminum wholly submerged in the electrolyte, and filmed aluminum connecting devices attached to alternate electrodes and extending outside the electrolyte for connection with an external circuit.

In testimony whereof we afiix our signatures in the presence of two subscribing witnesses.

RALPH D. MERSHON. JOHN-S. RIDDILE.

\Vitnesses:

M. LAWSON DYER, S. S. DUNHAM. 

